Automated inspection systems for ensuring the manufacture are well known. Systems are commonly used in processes including assembly verification, gauging, character verification and recognition, surface flaw detection, sorting systems, robotic guidance and like processes. For example, electro-optical sensing means are commonly used for detecting defects in transparent articles. In many of these applications, such systems provide inspection of 100 percent of the product.
In the metallic container manufacturing industry, the containers are transported in an empty, open-top condition during their manufacture prior to being packed. The bodies of the containers are often damaged in the open end neck or flange portion during their manufacture. In addition, containers often become dented, distorted or otherwise damaged rendering them unacceptable for further manufacture. If the container is dented or in any way damaged, it can create a jam-up in subsequent manufacturing operations, making it necessary to stop the entire production process and remove the jammed containers. Such a jamming occurrence also often results in good or acceptable containers being damaged, thereby increasing spoilage each time a jam occurs. This problem also arises where a container has been tipped or downed on the conveyor system.
An unavoidable consequence of such occurrences is the lost production time and increased spoilage. Conventional devices employed in this particular application often use mechanical means to allow defective containers to fall out of the manufacturing line. Most conventional high-speed ejection devices must eject several articles before and after a defective part to assure that the defective article is removed. Small part ejection devices usually consist of a compressed air jet or a small air cylinder ram for knocking the part from a single lane conveying device.
At increased conveying speeds and with close spacing of parts, it becomes especially difficult to eject lightweight parts. The difficulty is in a couple of areas. First, when a part is ejected rapidly, air currents are created which often displace adjacent parts. If the adjacent parts are displaced significantly, a conveying jam will occur. Second, as conveying speeds are increased, it is difficult to make the air cylinder ram extend and retract fast enough to properly eject a part and retract out of the way of the next advancing part and/or be ready to eject the next part should there be two (or more) adjacent defective parts. As noted, current practice is to eject several parts before and after the defective part to assure that the defective part is removed from the production flow. This practice generates unnecessary spoilage as good parts are sacrificed.
It has also become common to use vacuum devices in prior systems to automatically detect and reject downed cans. With devices of this type, a vacuum is normally applied to the open upper end of an upright container to hold the container against a moving conveyor while the downed cans will not be held against the vacuum mechanism and will drop down to a collection location generally below the vacuum mechanism.
One such apparatus for detecting and rejected downed and damaged containers is disclosed in U.S. Pat. No. 4,146,467 to Sauer, et al. This patent describes a transfer mechanism coupled to vacuum means wherein the vacuum holds the upper ends of the upright cans against the moving transfer mechanism so that the upright cans can be transferred from an upstream conveyor to a downstream conveyor. If the upper flange of the container is distorted in any way, possibly due to damage or denting of the sidewall of the container, the vacuum will be unable to hold the container against the transfer mechanism belt and the damaged can will be dropped from the transfer belt to a collection site located below.
There has developed a distinct need in the manufacturing industry to be able to identify and remove substantially all unacceptable articles from a continuous stream of articles being transported at high production speeds while reducing the spoilage of acceptable articles.